Tuesday afternoon after the papal Pallium Mass, the itinerary includes the catacombs of St. Callixtus and St. Paul’s Outside the Walls. I missed the catacombs on my first trip to Rome, so I’m really looking forward to this.

The visit to the catacombs begins with a brief introduction to the history and iconography of the period and the site. While the pagan Romans traditionally practiced cremation, the early Christians, in continuity with Jewish belief and custom refocused and refined in light of the resurrection of Jesus, placed a high premium on burying the dead in preparation for their rising. Because land was limited, starting in the second century Roman Christians (and Jews; a small number of Roman catacombs are of Jewish origin) acquired plots of land outside the city limits and dug massive underground labyrinths in the soft volcanic rock of the Roman countryside, carving out niches for burying the dead. The uniqueness of Judeo-Christian hope was even evident in the language they used: The standard pagan term for a burial site was “necropolis,” city of the dead, but the Christians early began calling their catacombs by a new name, “cemetery,” a term literally meaning “dormitory” or “place of sleep.”

Like many people, I once vaguely imagined the early Christians hiding out from Roman persecutions in the catacombs. In fact the catacombs were publicly known sites, not secret (our tour guide points out, commonsensically, that excavating tons of earth and rock along, say, the Appian Way could hardly be a surreptitious undertaking). The kernel of truth to the Hollywood picture is that during persecutions when Christian rites of worship could not openly be celebrated, Christians retreated to their underground burial sites, sacrosanct under Roman law, to celebrate the Eucharistic liturgy.

The introduction includes brief explanations of common Christian symbols—the chi-rho, the ichthys fish, the anchor, the shepherd, the alpha-omega—all accurate, but so fleeting that I suspect many pilgrims may not really absorb it.

Unlike most excavations in Rome, where the deeper you go the older stuff you find, the oldest catacombs are the nearest to the surface, and the deepest catacombs are the latest dug. The catacombs of Saint Callixtus go four levels deep, more than 65 feet below the surface, with twelve miles of galleries winding around a 90-acre plot of land. Nine popes and a number of other Roman prelates were buried here, along with innumerable other faithful. Many of the more notable remains have since been removed to other locations, but the soil remains hallowed.

Obviously, there is no way to see it all. Our tour takes us down to the third level. The heat of the day is left behind as we descend a modern staircase, built on the remains of an ancient one, into the cool darkness of the earth. Gathering in a chamber near the foot of the stairs, we see that in addition to artificial light there is also natural light: Shafts ascend upward through the levels above us to the surface. Our guide explains that these shafts were used to remove rock and earth as well as to provide light and ventilation.

Much of the catacombs look just the way you imagine them: dark, winding corridors with rows of niches carved into the walls on both sides from floor to roof far above our heads. Many are still sealed, walled over with brick or slabs of marble. Others are open, the remains long gone. Perhaps some were opened when the catacombs were besieged by Goths looking for burial wealth. (There wasn’t any.) Most of the relics, I suppose, were distributed for veneration. The niches are of all shapes and sizes: custom carved for the deceased, perhaps. Some are tiny, crypts for children or even babies. Very few look as if I might be able to lie down in them.

At one point I put out my hand and touch the floor of one of the niches. Loose soil comes off on my fingers. Immediately I feel guilty about this: If everyone did this, presumably the catacombs would erode away under their fingers. I rub off some of the soil, and then, impulsively, I touch my tongue to what’s left. Hey, the damage was done.

Some areas of the catacombs are different. In rooms hewn out for family burial there are much larger niches carved with apse-like arches. Within these niches, the burial spots were dug out, not horizontally into the back wall, but vertically, downward, like an above-ground grave. A marble slab was then placed over the remains, forming the bottom surface of the large niche: a natural table or altar where the Eucharist was celebrated, literally upon the tombs of the saints.

In some of these we find dim images going back to the second, third and fourth centuries: images representing baptism, the Eucharist and the resurrection of Christ. Other images date to later times, such as a ninth-century fresco depicting Christ Pantocrator, the Lord of All, in the crypt of St. Cecelia. There is also a much later statue of St. Cecelia herself, lying on her side, curled up as if asleep. With covert hand signs she claims her faith in one God in three Persons (one finger extended on her left hand, three fingers on her right).

The tour guide tries to keep us moving. Early on she joked about people getting lost in the catacombs every day. (It’s possible that people get separated from their groups, but there are way too many groups touring constantly in all different parts of the catacombs for anyone to be really lost.) The pace isn’t conducive to prayerful contemplation. A few times Sarah and I ignore the guide, kneeling to pray as the group moves on. Sometimes you have to make your own pilgrimage. We don’t get lost. (We pray the Our Father, which obviously was prayed here from the first day that ground was broken, and the Jesus Prayer, also ancient, though it probably wasn’t heard here until after the catacombs were no longer in active use.)

Toward the end we pass by a group celebrating a liturgy, in Polish I think. I would love to have Mass in the catacombs someday.

Writing about Mass at the crypt of St. Francis, I mentioned the unique experience of Francis’s personal charism and charisma. What I find in the catacombs is different. It’s less personal and palpably sacred, more archaeological and anthropological—in part perhaps because of the way the tour is conducted, but also, I think, in the nature of the site itself.

And yet, precisely because of this more archaeological and anthropological character of the catacombs, I am in a way nearer here to the historical figure of Jesus of Nazareth than I have ever been in my life.

St. Francis lived in the high Middle Ages, well over a millennium after Christ. The people who dug these corridors belonged to the ancient world of Jesus and the Apostles. They still lived under the shadow of the imperial power under which Jesus was crucified. They were separated from Jesus by only a few generations—closer in a way than we are to the time of Abraham Lincoln or George Washington, since the world has changed drastically from the times of Lincoln and Washington, whereas the Roman world in the second and third centuries hadn’t changed that much since the time of Jesus.

I’ve prayed before at the tombs of Peter and Paul. In those sites, finished in marble under two of Christendom’s grandest churches, there is a corporeal and spiritual connection to the Apostles, but no experience of their world. In the Vatican Museums I’ve seen artifacts of earliest Christianity, tiny etchings on bits of pottery and such: images of fish, of Peter and Paul, and so on. Here in the catacombs I’m surrounded by that world—not labeled and catalogued in a museum, but established in the earth like the oldest taproots of some ancient and massive tree. The walls around me, the floor under my feet and the roof over my head, the recesses yawning as far as the eye can see: All of this is a direct historical effect of the preaching of the Apostles. More than this, it’s a direct historical effect of their belief and preaching that Jesus had been raised from the dead.

Once again I can’t help thinking how awesome the scavi tour of the excavations under St. Peter’s Basilica would be. To see the actual burial place of Saint Peter himself—it would be like the catacombs and the crypt of St. Francis in one, but even more so. It would be about as close to the historical figure of Jesus as one could get outside of the Holy Land, mediated through the central New Testament personality of Simon Peter, the fisherman, the bungler, the rock. (I had thought beforehand that the scavi tour could be arranged a few days ahead of time, but alas, it turns out it’s booked weeks in advance.)

We return to the light and heat of the surface, but new ground has been excavated in my soul. Next: More Paul and Peter.